Pseudoephedrine is a beneficial drug which occurs naturally in plants of the genus Ephedra. Pseudoephedrine is a stereoisomer and the isomeric forms include d- and l-ephedrine as well as d- and l-pseudoephedrine and racemic mixtures thereof. The drug pseudoephedrine is administered as its pharmaceutically acceptable acid addition salt. The organic and the inorganic salts used include organic salts such as ascorbate, bitartrate, citrate, fumarate, malicate, maleicate, succinate, tartrate and the like, and inorganic salts such as the hydrochloride, nitrate, phosphate, sulfate and the like.
Pharmacological pseudoephedrine is a sympathomimetic amine. Pseudoephedrine is used as a bronchodilator and as a peripheral vasoconstrictor. Pseudoephedrine is indicated for temporary relief of nasal congestion due to the common cold, for temporary relief of nasal congestion associated with sinusitis, for relief of cough due to minor throat irritation as may occur with the common cold or inhaled irritants, for promoting nasal drainage, for promoting sinus drainage, for its help in loosening phlegm and bronchial secretion, for helping rid the bronchial passage of mucus, for relief of hay fever, and for the relief of upper respiratory allergies. The therapeutic properties of pseudoephedrine are known to the medical arts in Pharmaceutical Sciences, by Remington, 17th Ed., p 890, 1985; The Pharmaceutical Codex, 11th Ed., p 761, 1981, and The Extra Pharmacopoeia, by Martindale, 28th Ed., p 27, 1982.
While pseudoephedrine enjoys wide acceptance by the medical-dispensing arts for its intended therapeutic indications, there are serious disadvantages associated with its use. For example, one disadvantage known to the prior art is that the medical-dispensing arts lack a dosage form that could sustain the administration of the medication at a known amount per unit time for a predetermined length of time, in contrast to the presently used conventional tablets and capsules that are administered every four hours and immediately releases all of its medication. Another disadvantage associated with the prior art drug is its instability to light, and it can be subjected to chemical attack by many agents that are used conventionally in pharmaceutical preparations.
In the light of the above presentation it will be appreciated by those versed in the dispensing arts to which this invention pertains that a critical need exists (1) for a dosage form that can deliver pseudoephedrine at a controlled rate to provide a dosage, therapeutic administration of pseudoephedrine for its beneficial effects over a prolonged time span; and (2) for a dosage form that can concomitantly and substantially provide shelter from light during storage, manufacture, and the like, and administer the medication essentially independent of individual chemical variations in an environment of use such as the gastrointestinal tract. It will be further appreciated by those versed in the art that such a novel and unique dosage form that can administer pseudoephedrine at a controlled rate over time, and simultaneously provide substantial protection from adverse effects, would represent an advancement in the art and it would also represent a valuable contribution to the art.